Project Summary Present cell-based techniques of prenatal diagnosis such as amniocentesis, chorionic villus sampling (CVS) and percutaneous umbilical blood sampling (PUBS) are invasive and present significant risks of fetal loss. Non-invasive prenatal diagnosis utilizing fetal cells circulating in maternal peripheral blood during pregnancy has received much attention since it poses no risk to the fetus. Although several fetal cell types have been targeted, the search has focused on fetal nucleated red blood cells (fNRBC). However, because of very low concentration of fNRBC in the maternal blood, interference by nucleated red blood cells of maternal origin (mNRBC) and the failure to find broadly applicable identifiers that can differentiate fNRBC from mNRBC reliable detection and isolation of viable cells in amounts sufficient for clinical use remains a monumental challenge. Fetal NRBC differ from maternal NRBC in both nuclear morphology and hemoglobin molecular structure. Recently the principal investigator and his colleagues at MIT have developed biomedical light scattering spectroscopy (LSS) and showed its unique ability to optically probe nuclear morphology without damaging cells. Our group has further advanced LSS and developed the confocal absorption and scattering spectroscopic technique (CLASS) capable of monitoring subcellular organelles in small confocal volumes. The objective of this research program is twofold. (1) We will use the existing CLASS equipment developed in our laboratory to identify fNRBC native optical biomarkers. (2) Based on these biomarkers, we will develop a fast, simple and robust optical technique which combines CLASS microscopy and optical tweezers in the same instrument and which will enable enrichment and recovery of intact fNRBC from a sample of maternal peripheral blood. This will lead to a clinically useful method for prenatal genetic testing.